I’ve split my file into 5 now. There is moveGeneration.py which calculates all the legal moves, moveExecution.py which actually moves the pieces, updateBoard.py which updates the board, gui.py which handles graphics (like arrows, promotion page and clicks) and main.py which says what functions should happen when an input is given and has a while loop for while the game is running (as is needed by pygame). Splitting the file makes it much easier to debug, keep track and add features instead of just having one ~1000 line file where everything is jumbled up. Next I am going to start work on the actual bot.